The growth rate and clinical outcomes of radiation induced meningioma undergoing treatment or active monitoring

Abstract

Introduction: Radiation induced meningioma (RIM) incidence is increasing in line with improved childhood cancer survival. No optimal management strategy consensus exists. This study aimed to delineate meningioma growth rates from tumor discovery and correlate with clinical outcomes.

Methods: Retrospective study of patients with a RIM, managed at a specialist tertiary neuroscience center (2007-2019). Tumor volume was measured from diagnosis and at subsequent interval scans. Meningioma growth rate was determined using a linear mixed-effects model. Clinical outcomes were correlated with growth rates accounting for imaging and clinical prognostic factors.

Results: Fifty-four patients (110 meningiomas) were included. Median duration of follow-up was 74 months (interquartile range [IQR], 41-102 months). Mean radiation dose was 41 Gy (standard deviation [SD] = 14.9) with a latency period of 34.4 years (SD = 13.7). Median absolute growth rate was 0.62 cm³/year and the median relative growth rate was 72%/year. Forty meningiomas (between 27 patients) underwent surgical intervention after a median follow-up duration of 4 months (IQR 2-35). Operated RIMs were clinically aggressive, likely to be WHO grade 2 at first resection (43.6%) and to progress after surgery (41%). Median time to progression was 28 months (IQR 13-60.5). A larger meningioma at discovery was associated with growth (HR 1.2 [95% CI 1.0-1.5], P = 0.039) but not progression after surgery (HR 2.2 [95% CI 0.7-6.6], P = 0.181). Twenty-seven (50%) patients had multiple meningiomas by the end of the study.

Conclusion: RIMs exhibit high absolute and relative growth rates after discovery. Surgery is recommended for symptomatic or rapidly growing meningiomas only. Recurrence risk after surgery is high.

Keywords: Meningioma; Natural history; Radiation; Radiation induced meningioma; Volumetric growth.

Fig. 1

Patient management showing treatment strategy after diagnosis and subsequent management. RIM radiation induced meningioma, FRT fractionated radiotherapy, SRS stereotactic radiosurgery

Fig. 2

Volume time plots demonstrating. a All RIM patients with volumetric analysis. b Growth plots of RIMs that met standard growth definition of AGR ≥ 2 cm³/year or AGR ≥ 1 cm³/year and RGR ≥ 30% per year. c Growth plots of RIMs that did not grow during the study period and d meningioma growth after surgery

Fig. 3

Kaplan Meier curves demonstrating Kaplan Meier curves demonstrating. a Growth-Free survival, b intervention-free survival, c progression-free survival after surgery, and d multiple-free survival in RIM patients